Society girls getting to grips with tango? They're liabilities! (5)
I believe the answer is:
debts
'liabilities' is the definition.
('debt' can be a synonym of 'liability')
'society girls getting to grips with tango?' is the wordplay.
'society girls' becomes 'debs' (debutantes).
'getting to grips with' is an insertion indicator.
'tango?' becomes 'T' (phonetic alphabet: alpha, bravo, charlie etc.).
'debs' placed around 't' is 'DEBTS'.
'they're' is the link.
(Other definitions for debts that I've seen before include "Monies owed" , "Outstanding sums" , "Financial obligations" , "Liabilities" , "Amounts owed" .)